Re: iio: adc: KASAN wild-memory-access in complete() on early IRQ

[Maxwell Doose]

On Wed, Jun 10, 2026 at 7:04 AM Jaeyoung Chung <jjy600901@xxxxxxxxx> wrote:
>
> Hi,
>
> lpc32xx_adc_probe() in drivers/iio/adc/lpc32xx_adc.c and
> spear_adc_probe() in drivers/iio/adc/spear_adc.c register their
> interrupt handler with devm_request_irq() before they initialize
> st->completion with init_completion(). If an interrupt arrives after
> devm_request_irq() and before init_completion(), the handler calls
> complete() on an uninitialized completion, causing a kernel panic.
>
> The probe path, in lpc32xx_adc_probe():
>
>     iodev = devm_iio_device_alloc(&pdev->dev, sizeof(*st)); /* st kzalloc-zeroed */
>     ...
>     retval = devm_request_irq(&pdev->dev, irq, lpc32xx_adc_isr, 0,
>                               LPC32XXAD_NAME, st);           /* register handler */
>     ...
>     init_completion(&st->completion);                       /* initialize completion */
>
> spear_adc_probe() has the same ordering: devm_request_irq() for
> spear_adc_isr() before init_completion(&st->completion).
>
> Both interrupt handlers, lpc32xx_adc_isr() and spear_adc_isr(), call
> complete():
>
>     complete(&st->completion);
>
> If the device raises an interrupt before init_completion() runs,
> complete() acquires the uninitialized wait.lock and walks the zeroed
> task_list in swake_up_locked(). The zeroed task_list makes list_empty()
> return false, so swake_up_locked() dereferences a NULL list entry,
> triggering a KASAN wild-memory-access.
>
> Suggested fix: move init_completion(&st->completion) above
> devm_request_irq(), so the completion is valid before the handler can run.
>
> Reported-by: Sangyun Kim <sangyun.kim@xxxxxxxxx>
> Reported-by: Kyungwook Boo <bookyungwook@xxxxxxxxx>
>

Thanks for reporting this; I can start working on a fix shortly
(assuming nobody else is already working on it).


--
best regards,
max